Yes I understand, and no problem here. This is a hard arguement its the same companies new vs old. I think Fluval has held back the C5 on purpose because it would blow away the 406 and add competition. I have a bad habit of calling something just as I see it which is not always a good thing

. The C has fixed some of the issues with the AC line rather a person wants to admit it or not. The AC line is not as good at mechnical since they changed the sponges. If the AC gets clogged the assembly will start to float up to where it can overflow or at least dry out what in most cases is your Biomax. The plastic seems to fit better like covers. And it's as easy if not easier to service. Plus the added Bio. I agree it's not ment to compete with the 110 Fluval isn't stupid but they have realized what they are going to need to compete and not loose the business rather or not it is ment to replace the AC someday is yet to be seen. But the new models and the phaseout of the Aquaclear name sure points in that direction. Now there Canisters don't get me started I've got three I can't afford to replace so I'm stuck until I get rich or win the lottery. A whole another subject which I have given up on!!!!